Sri Lankan Journal of Applied Sciences

Investigation of Drying Characteristics and Estimation of Mass Transfer Parameters of Sri Lankan Black Pepper Dried in a Batch Fluidized Bed Dryer.

B.M.W.P.K. Amarasinghe — 2025-02-28

The drying of Sri Lankan black pepper was studied using a lab-scale batch fluidized bed dryer at three different temperatures of 55 ^°C, 65 ^ºC, and 75 ^ºC. Minimum fluidization velocities were determined for different bed weights. The effect of drying temperature and bed weight on the drying rate of black pepper in a fluidized bed was studied. Higher drying rates were observed at higher drying air temperatures and lower bed weights. Experimentally determined moisture ratios with time were fitted into twelve thin-layer drying models. Statistical indicators: Coefficient of determination (R²), Root mean square error (RMSE) and reduced chi-square values (c2) showed that the Midilli et. al model gives the best fit to the experimental values to describe the drying of black pepper in the fluidized bed. The absence of the constant drying rate period in drying curves shows the drying of black pepper lies totally in the falling rate period where the drying rate is controlled by moisture diffusion. Maximum drying rates observed were 1.7, 3.8, and 5.9 kg moisture/kg of dry material per minute at 55 ^˚C, 65 ^ºC, and 75 ^ºC drying temperatures respectively. Results revealed drying rate constant and the effective moisture diffusivity values increase with the hot air temperature. Drying rate constants in the Midilli et. al model were 0.0055, 0.0109, and 0.0197 min^-1 and the effective moisture diffusivity values were 1.071 × 10^-10, 2.032 ×10^-10, 2.844 × 10^-10 m²/s for 55 ^˚C, 65 ^ºC and 75 ^ºC of drying temperatures respectively. The activation energy for moisture diffusivity was 46.518 kJ/mol.

Keywords: Black pepper, Fluidization, Drying, Diffusivity, Mass transfer, Activation energy

Gamma Irradiation of Export Oriented Moringa Leaf (Moringa oleifera) Powder and Flakes for Microbial Safety

K.M.S.P.L. Karunanayake — 2025-02-28

Gamma irradiation is a well-accepted innovative technology. This study was carried out to evaluate the effect of different gamma irradiation doses on physical parameters, and microbial quality of export oriented Moringa powder and flakes in Sri Lanka. Homogenized Moringa samples were collected from a particular exporter. Samples were irradiated at doses of 0 kGy, 2 kGy, 4 kGy, 6 kGy, 8 kGy and 10 kGy by industrial Co-60 gamma irradiator. Under physical parameters, water activity, moisture content, colour and infusion colour (in Hunter colour scale) were measured for each of the treatment. Under microbial safety total plate count (TPC), yeast and mold count and coliform counts (total coliform, fecal coliform and E. coli) were measured. All treatments were triplicated. Average moisture content of irradiated Moringa powder and flakes were 6.32±0.04% and 6.09±0.03% respectively. Average water activity of irradiated Moringa powder was 0.41±0.00 and irradiated Moringa flakes was 0.44±0.03. Mean values of colour and infusion colour of irradiated Moringa powder and flakes were not significantly different (P<0.05) with the control sample. The average TPC in control sample of Moringa powder was 1.29×10⁷±2.46×10⁵CFU/g and Moringa flake was 4.20×10⁵±3.71×10⁵ CFU/g, where irradiated samples show drastic reduction with the dose. The average Yeast and Mold counts in the control sample of Moringa powder was 3.11×10²±6.80×10¹ CFU/g and Moringa flake was 2.30×10²±2.06×10² CFU/g, where irradiated samples show sterilized conditions. E. coli were identified in 0 kGy and 2 kGy samples only. All irradiated samples showed significant reduction (p<0.05) of TPC, yeast and mold and coliform counts in both Moringa powder and flakes. It is concluded that the 6 KGy is better for Moringa flake and 8 kGy is better for Moringa powder for microbial safety while preserving the physical and chemical properties.

Keywords: Moringa, Gamma irradiation, Dose, Microbial safety, Quality changes

Assessing the Impact of Mimosa pigra – Derived Bio-Fertilizer on Selected Growth and Yield Parameters in MI-2 Chili (Capsicum annum)

T.M.M.P.S. Bandara — 2025-02-28

This study was investigated the effect of Mimosa pigra (MP) based fertilizer on the selected growth and yield parameters of MI-2 chili. This organic fertilizer was produced by cutting Mimosa pigra into smaller pieces during its vegetative stage and kept them into separate pits for six months until they decompose. The manure produced from the decomposed of MP was extracted from the pit, and used to form several distinct piles with specific compositions. One treatment was produced by incorporating with MP. Another treatment was consisted by incorporating with MP and CaCO₃ (MPC). The third treatment was made by combining with MP and Inorganic fertilizer (MPIF). A negative control treatment was prepared for comparison and each mixture consisted of combination of garden soil, goat manure and sand in a 2:2:1 ratio. ANOVA test and Duncan’s multiple range analysis were exploited using Minitab 17 software at 95% confidential interval. According to the findings, crops treated with MP showed a significantly high mean number of branches (23.89) , mean number of pods (10.17) , mean number of harvested pods (4.62), high mean weight of pods (8.28 g), pods length (4.38 cm), diameter of pods (0.8540 cm), and the number of seeds per pod (38.00), but there was no significant difference in the height of the plants (P=0.694) and mean number of flowers (P=0.48) which were treated with MP. In conclusion, the MP derived fertilizer has the potential to promote more sustainable and environmentally- friendly agricultural practices in Sri Lanka by providing a practical solution for managing and controlling invasive plant species through their effective utilization as a valuable resource for producing an alternative to traditional fertilizer.

Keywords: Mimosa pigra, Organic fertilizer, Vegetative stage

Determination of Glycemic index and the consumer preference of Borassus flabellifer treacle as an alternative sweetener among a selected group of undergraduates in Sri Lanka

M.R.K. Farween — 2025-02-28

The Borassus flabellifer treacle, commonly known as Palmyrah treacle in Sri Lanka, is a well-known local traditional sweetener. This study was performed to determine its glycaemic index (GI) and assess consumer preferences among undergraduate students at KAATSU International University, Sri Lanka. A self-administered questionnaire (n=281) was used to survey participants’ knowledge of diabetes mellitus (DM) and Borassus flabellifer treacle, to collect information regarding consumer purchasing trends, health status, and preferences. For the GI study, 30 healthy undergraduate students from KAATSU International University were selected as subjects. Each participant consumed a food containing 50g of carbohydrates after fasting. Capillary blood was taken at fasting,15,30,45,60, and 120 min after the meal. The GI was calculated by dividing the incremental area under the curve for the treacle by the glucose and multiplying by 100. The study revealed that the majority of respondents (39.9%) have good knowledge regarding treacle consumption, 26.0% of respondents have average knowledge and 34.2% number of respondents have poor knowledge. The GI value of Borassus flabellifer treacle was 61.72±17.44, which belonged to the medium GI category, highlighting its potential role in managing and preventing DM and other non-communicable diseases.

Keywords: Borassus flabellifer treacle, Consumption, Glycemic Index, Undergraduates

Antagonistic Yeast-based Biocontrol against Penicillium sp. Spoilage for Prolonging the Shelf Life of Tomatoes (Solanum lycopersicum)

R.A.O.P. Ranasinghe — 2025-02-28

The tomato (Solanum lycopersicum) is the second most extensively cultivated crop globally. However, an estimated 25% to 42% of the worldwide tomato yield is lost during the post-harvest stage, primarily due to various factors, including pathogen infections. Especially, Penicillium species are a significant cause of post-harvest losses, particularly under refrigerated storage conditions. Antagonistic yeasts have shown promising potential in controlling fungal pathogens. Therefore, this study focuses on isolating yeasts and evaluating their antagonism against Penicillium sp. to enhance the shelf life of tomatoes. Four yeast strains were isolated from soil and citrus leaves (YS004, YCL001, YCL002, YCL004),and Penicillium sp. was isolated from infected tomatoes. A dual culture assay was conducted to evaluate the antagonistic activities of each yeast strain against Penicillium sp. Three yeast strains had shown significant antagonistic activity against Penicillium sp. (one-way ANOVA, p < 0.05), yet only YS004 (68.27 ± 0.33) exceeded the 55% of percent inhibition of radial growth (PIRG). In the in vivo assay, tomatoes treated with YS004 (4.04 × 10^-5cells mL^-1) exhibited the lowest disease severity percentage of 45 ± 2.89 and the lowest disease incidence of 43.33 ± 5.77%. The tomatoes treated with YS004 achieved a shelf life of 19 days compared to 12 days for the control samples. Also, tomatoes treated with YS004 showed statistically significant retention of moisture content (p = 0.0000; p < 0.05) and reduced weight loss (p = 0.0000; p < 0.05). A sensory evaluation was done using 30 untrained panellists, and the results indicated that YS004 enhanced the overall acceptability of tomatoes. Therefore, applying the YS004 yeast solution is a promising and effective bio-control agent that can extend the shelf life of tomatoes by controlling the Penicillium pathogen in refrigerated conditions.

Keywords: Antagonistic yeast, Penicillium spp., Dual culture assay, Shelf life, In vivo assay

Bioassay Guided Fractionation of Anti-Hyperglycemic Compounds Extracted from Cheilocostus Specious, and Model Development for Sustained Release of Anti-Hyperglycemic Compounds Using Acarbose

L.L. Edirisinghe — 2025-02-28

Cheilocostus speciosus (COS) leaves are traditionally used for managing diabetes, though prolonged consumption risks severe hypoglycemia. This study explored anti-hyperglycemic compounds from ethanol extracts of COS leaves and developed a sustained drug delivery system using montmorillonite (MMT). Ethanol extracts showed strong α-amylase and α-glucosidase inhibition (IC₅₀: 14.62 ppm and 21.20 ppm), comparable to acarbose, a standard diabetic drug. Active fractions were isolated via gravity column, size exclusion, and thin-layer chromatography, confirming COS leaves’ anti-hyperglycemic potential. To enhance therapeutic applicability, acarbose was intercalated into MMT as a nanocarrier for sustained release. X-ray diffraction confirmed increased interlayer spacing (1.185 nm to 1.403 nm) when increased acarbose concentration from 50-100 ppm, while intensified OH stretching peak in FTIR indicated acarbose integration into the clay matrix. Intercalation efficiency improved with higher acarbose concentrations (43.77% to 52.27%). In-vitro studies revealed controlled acarbose release over 8 hours (45.66%) and sustained slow release, following pseudo-second-order kinetics (r² = 0.9767). These findings suggest COS as a promising source of anti-diabetic compounds and highlight MMT's potential as a nanocarrier for safer, sustained therapies. Future research will focus on large-scale isolation, structural elucidation, and integration of active compounds into MMT for enhanced diabetic treatments.

Keywords: Cheilocostus speciosus, Ethanol extract, α–amylase inhibitor, α–glucosidase inhibitor, montmorillonite, sustained drug release

Study of Nano Metal Oxide Incorporated Zinc Phosphate Coatings as Corrosion Inhibitors on Mild Steel

B. Neelampary — 2025-02-28

The existing corrosion prevention processes and methods are incapable of predicting all environmental conditions. On the other hand, the local metal coating and paint industries continue to suffer from a lack of appropriate advanced phosphating technology as a surface pre-coating technique. The incorporation of ceramic nanoparticles into the phosphate coating has improved the properties such as high corrosion resistance and secondary coating adhesion. As a result, the goal of this research was to create and improve a corrosion prevention method suitable for the metal coating industries by incorporating nano TiO₂ into a phosphate precoating. To facilitate the coating via chemical conversion, the cleaned mild steel specimens were dipped in the prepared phosphating bath containing the nano TiO₂. Under the given conditions, the optimum coating time was determined to be 90 minutes. Significant changes in coating weight, adhesion quality, surface porosity, and corrosion resistance were observed with the addition of nano TiO₂ (average particle size ~ 25 nm). X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and a gemmological microscope were used to investigate the crystal phases and surface morphology of zinc phosphate coatings. XRD data clearly showed that nano TiO₂ has successfully incorporated into the phosphate layer. The addition of nano TiO₂ to the zinc phosphate coating improved its properties, such as coating thickness and surface area, promising an improvement in corrosion resistance. With minor modifications aiming to lower the coating time, the findings of this study could be easily implemented in the metal coating industries and extended to other metals such as steel, aluminium, and alloys.

Keywords: Chemical Conversion, nano -TiO₂, Mild steel, Phosphating

Integrated mutation strategies in a biologically inspired algorithm to solve the vehicle routing problem with moving shipments at the cross-docking centre

S.R. Gnanapragasam — 2025-02-28

The cross-docking is an innovative logistic technique in a supply chain. In a previous study, some internal operations at the cross-docking centre were integrated to develop a model for the Vehicle Routing Problem with Moving Shipments at the Cross-Docking Centre (VRPCD-MS). However, only the small-scale instances were used to obtain the exact-optimal solution and the study recommended applying meta-heuristic approaches to reach near-optimal solutions to the large-scale instances of VRPCD-MS. This study attempts to employ Genetic Algorithm (GA) with multiple-mutation strategies ‘SWAP’ and ‘REVERSION’ to solve VRPCD-MS. Initially, GA with SWAP and GA with REVERSION mutation strategies are employed sequentially as two different approaches. Consequently, the solutions of the benchmark problems reveal that there is no strong evidence to recommend any of those two approaches is better than the other. Furthermore, the two-sample t-test concludes that, there is no significant difference in solutions by applying these two mutation strategies alone. It can be concluded that, up to 30% improvement in the solution can be obtained by using GA with merged SWAP and REVERSION mutation strategies together. It further concludes that, on an average, nearly 15% improvement in the solution is reached by the integrated mutation strategies in the proposed GA approach.

Keywords: Cross-docking, Genetic Algorithm, REVERSION mutation, SWAP mutation

Applications of Artificial Intelligence in Healthcare: Current Trends and Future Prospects

O.V. Rajapaksha — 2025-02-28

Artificial Intelligence (AI) is highly valuable across various fields, including the healthcare sector; it improves the precision of diagnosis, the effectiveness of recommended treatment options, and the adaptation of medical care plans. This review paper will look at how the existing literature has applied AI and will do this under the following subheadings: diagnostics, treatment, and individualized therapy. Moreover, the paper describes the effects of applying AI on the state of patients and the effectiveness of the healthcare industry as well as present trends and considers the further development of the role of AI in the healthcare future along with the potential problems that may occur.

Keywords: AI, medicine, diagnostics, treatment advice, individualized medicine, patients’ effects, health care organization.